1. Field of the Art
This invention relates to an ultrasound examination system, and more particularly to an ultrasound probe which can be introduced into a body cavity through a narrow guide passage like a biopsy channel of an endoscope or the like.
2. Prior Art
Ultrasound probes of the sort which are adapted to be inserted into a body cavity by way of an endoscope or a similar guide means have been well known in the art and widely used for ultrasound examination systems. For instance, Laid-Open Japanese Patent Application H11-56836 discloses an ultrasound examination system employing an ultrasound probe which is designed to be introduced into a body cavity through a biopsy channel of an endoscope. The ultrasound probe of this ultrasound examination system has an ultrasound scanner head with an ultrasound transducer element, attached to the fore distal end of a flexible cord to be inserted into an endoscopic biopsy channel. A connector is provided at the base or proximal end of the flexible cord for connection to an ultrasound image observation terminal with an ultrasound signal processor and a viewing screen.
In a case where an endoscopic biopsy channel is used as a guide means, as a matter of course the outside diameter of the ultrasound probe depends on the inside diameter of the endoscopic biopsy channel. In this regard, it is the flexible cord of the probe that is placed within a biopsy channel of an endoscope. The ultrasound probe may be introduced into an endoscopic biopsy channel either through an entrance opening of the biopsy channel through which a biopsy or surgical instrument is normally inserted into the biopsy channel or inversely through an exit opening through which an inserted biopsy or surgical instrument is projected within a body cavity. This means that at least one end of the ultrasound probe is free from diametrical restrictions as imposed by the inside diameter of the biopsy channel. Namely, the diameter of the ultrasound scanner head at the fore distal end of the flexible cord or of the connector at the proximal end f the flexible cord can be larger than that of the endoscopic biopsy channel. In the case of the prior art ultrasound probe mentioned above, the ultrasound scanner head which accommodates a large-size ultrasound transducer element is larger than the endoscopic biopsy channel in diameter, while the flexible cord and connector are formed smaller than the inside diameter of the biopsy channel. Because of fragility of the thin and narrow connector, an adaptor is detachably attached to the connector at the time of coupling same with an ultrasound scan control unit which is connected from an ultrasound image observation terminal.
In this instance, the ultrasound transducer which is provided on the above-mentioned prior art ultrasound probe is of a single-element type which is adapted for mechanical radial scans. For this purpose, threaded through the flexible cord is a flexible transmission shaft having tightly wound coils fitted within a flexible sleeve to transmit rotations to the ultrasound transducer element, which is connected to the fore distal end of the flexible shaft. The opposite base end of the flexible shaft is coupled with a rotational shaft which is provided within the connector. The rotational shaft of the connector is connected to a drive shaft which is provided within a casing of the ultrasound scan control unit, along with an electric drive motor which is coupled with the drive shaft and an encoder which is provided in association with the drive shaft to detect rotational angles of the latter.
In addition to the ultrasound probes of the above-mentioned mechanical radial scan type, there have been in use the so-called electronic scan type ultrasound probes. In the case of an electronic scan type probe, the ultrasound transducer consists of a large number of transducer elements which are arranged in a predetermined direction, for example, in a linear direction or in radial directions. A signal cable is connected to each one of the ultrasound transducer elements to transmit and receive ultrasound signals separately by the respective transducer elements. In the case of an electronic scan type ultrasound probe of this sort, the pattern or focus position of an ultrasound scan can be changed to cope with various ultrasound examinations, by suitably adjusting the drive timing of the respective ultrasound transducer elements.
Since the ultrasound transducer on an electronic scan type probe contains a large number of transducer elements, it is difficult to reduce its diameter down to a size which can easily pass through a biopsy channel of an endoscope. However, as in the case of the above-mentioned prior art probe construction, the ultrasound probe can be placed in an endoscopic biopsy channel by inserting the probe through an exit opening of the biopsy channel at the fore distal end of the endoscope. For an electronic scan type ultrasound probe, it is not necessary to have a flexible transmission shaft within the flexible cord which is connected to the ultrasound scanner head. Therefore, a necessary number of signal cables can be relatively easily passed through the flexible cord if the diameter of each signal cable is reduced to a suitable degree. However, in the case of an electronic scan type ultrasound probe which requires a large number of contact points, it becomes necessary to provide a large connector at the proximal end of the flexible cord. In short, in the case of an electronic scan type probe, larger the number of the ultrasound transducer elements, larger becomes the size of the connector. Therefore, even if the flexible cord of an electronic scan type probe is thin and narrow enough for passage through an endoscopic biopsy channel, it has been often found difficult to insert the probe into a narrow guide channel or passage of an endoscope because of bulkiness of the ultrasound scanner head and the connector which are provided at the head and tail ends of the flexible cord, despite various advantages of electronic scan type probe in ultrasound examinations.
Under the circumstances as discussed above, it is an object of the present invention to make it possible to insert and place an electronic scan type ultrasound probe into a narrow passage like a biopsy channel of an endoscope.
It is another object of the present invention to make it possible to insert into and pass through a narrow guide passage a connector portion which is provided at the proximal end of a flexible cord of an electronic scan type ultrasound probe and which usually incorporates a large number of terminals for connection to an ultrasound signal processor of an ultrasound image observation terminal.
In order to achieve the above-stated objectives, according to the present invention, there is provided an ultrasound probe for use on an ultrasound examination system which is largely composed of an ultrasound probe to be introduced into a body cavity by way of a guide passage and an ultrasound image observation terminal, the ultrasound probe including an ultrasound scanner head attached to a distal end of a flexible cord to be placed in the guide passage at the time of introduction into a body cavity and constituted by a plural number of ultrasound transducer elements for making electronic scans, a plural number of signal lines passed through the flexible cord and connected respectively to the ultrasound transducer elements, a proximal end portion of the flexible cord being led out of the guide passage and disconnectibly connected to an ultrasound signal processor of the ultrasound image observation terminal, characterized by the provision of: a flexible wiring film in the shape of a relatively narrow strip having a root end portion thereof fixedly attached to a proximal end portion of the flexible cord of the ultrasound probe and adapted to be coiled into a helical roll of a cylindrical shape along an axial extension line of the flexible cord for passage through the guide passage; the flexible wiring film having a plural number of wire connection points formed on a surface thereof at positions closer to the root end for connection thereto of the signal lines from the ultrasound transducer elements, and a plural number of electrodes formed in intermediate and opposite end portions and each connected with a corresponding one of the wire connection points through a wiring pattern; the electrodes of the flexible wiring film being adapted to be disconnectively connected to contact points provided on a contact unit of a relay means.
An ultrasound probe is introduced into a body cavity to transmit and receive ultrasound signals through an intracavitary wall. However, the ultrasound is not introduced into a body cavity by itself. It is usually inserted through a guide passage, typical of which is a biopsy channel which is provided on an endoscope. Besides the biopsy channel, other guide means can be used for introduction of the ultrasound probe. Regarding the ultrasound transducer, the respective transducer elements may be arrayed circularly, arcuately or linearly depending upon the mode of electronic scans.
The flexible wiring film, a wiring board in the form of a flexible film, is attached to a proximal end portion of the flexible cord of the ultrasound probe. In this regard, the flexible wiring film can be formed integrally with a sheathing tube of the flexible cord. However, from the standpoint of efficiency of fabrication process, it is desirable to form the flexible cord and the flexible wiring film separately, fixing the flexible wiring film on the sheathing tube of the flexible cord afterwards. The flexible wiring film may be bonded on a circumferential surface of the sheathing tube of the flexible cord. However, in order to facilitate connections of signal lines from the flexible cord, it is more desirable to provide an longitudinal slot-like opening of a suitable length in a proximal end portion of the sheathing tube and to securely fix the root end portion of the flexible wiring film within the slot-like opening.
The wire connection points are formed in a row or rows and at positions in the proximity of the slot-like opening in the sheathing tube of the flexible cord. The signal lines that are led out of the flexible cord are connected to the wire connection point by soldering. These wire connection points, wiring pattern and electrodes can be formed on the flexible wiring film, for example, by the use of a printing means. For connection of the signal lines, each one of the wire connection points suffices to have a small surface area. Accordingly, the wire connection points can be located collectively on a root end portion of the flexible wiring film. On the other hand, the electrodes to be brought into and out of engagement with the contact points on the side of the contact assembly of the relay means need to have a broader surface area as compared with the wire connection points. Accordingly, the electrodes having a broader surface area are located dispersedly in intermediate and opposite outer end portions of the flexible wiring film. Thus, the width and length of the flexible wiring film are determined mainly in relation with the size and number of the electrodes. Especially, the length of the flexible wiring film can be increased to a sufficient degree, if necessary, because the film is coiled into the shape of a partially overlapped helical roll at the time of passage through a guide passage.
When coiled into the shape of a helical roll, the flexible wiring film should be easily passable through a narrow guide passage. For this purpose, the flexible wiring film is rolled into a cylindrical shape gradually from the root end portion which is connected to the flexible cord of the probe. In the case of a flexible wiring film with a broader surface area, in order to hold the flexible wiring film stably in the coiled shape, that is, in the cylindrical shape, it is desirable to extend the flexible wiring film obliquely in the rearward direction relative to the longitudinal axis of the flexible cord of the probe. By so doing, the flexible wiring film strip can be easily coiled into a partially overlapped helical roll. To prevent uncoiling or unrolling of the rolled flexible wiring film, it is necessary to stop the free end of the film. For this purpose, a rubber band or an adhesive tape can be used. Alternatively, a flexible sheath member may be fitting on the free end of the film. Further, the flexible wiring film may be imparted with a convolving traits beforehand in order to facilitate the job of coiling same into a partially overlapped helical roll.
For connection to contact points, the flexible wiring film needs to be set in a flat state on the contact unit. For this purpose, the contact unit is constituted by a contact assembly and a pressing member. A predetermined number of contact points are provided on a top surface of the contact assembly correspondingly to the electrodes on the side of the flexible wiring film which is set on the top surface, and the pressing member is closed on the contact assembly, pressing the interposed flexible wiring film against the contact assembly to electrically connect the electrodes to the corresponding contact points on the contact assembly. Alternatively, arrangements may be made to fix the flexible wiring film on the contact assembly by the use an adhesive or other means. One side of the pressing member can be flexibly connected to one side of the contact assembly by the use of a hinge or hinges. In this case, for locking the pressing member in a closed pressing position on the contact assembly, it is desirable to provide a lock means between these members.
Preferably, a resilient pad member, for example, is provided on an inner surface of the pressing member thereby to electrically connect the electrodes of the flexible wiring film with the contact points on the contact assembly securely in a reliable manner. Further, for positioning the electrodes of the flexible wiring film correctly relative to the contact points on the contact assembly, it is desirable to provide a plural number of positioning projections on the top surface of the contact assembly for engagement with positioning perforations which are provided on the side of the flexible wiring film. Of course, the electrodes on the flexible wiring film can be brought into position relative to the contact points on the contact assembly in reference to the shape of the flexible wiring film and a marking which is provided on the top surface of the contact assembly. Further, preferably, the contact assembly is constituted by contact pins which are retractably projected on the top surface of the contact assembly and spring member which are adapted to bias the contact pins in a projecting direction.
The above and other objects, features and advantages of the present invention will become apparent from the following particular description of the invention, taken in conjunction with the accompanying drawings. Needless to say, the present invention should not be construed as being limited to particular forms shown in the drawings which show by way of some preferred embodiments of the invention.